A coordinate measuring device is well-known from prior art. See, for example, the lecture script “Pattern Placement Metrology for Mask Making” by Dr. Carola Bläsing. The lecture was given on the occasion of the Semicon conference, Education Program, in Geneva on Mar. 31, 1998, and described the coordinate measuring machine in detail. The structure of a coordinate measuring machine as known, for example, from prior art will be explained in more detail in the following description associated with FIG. 1. A method and a measuring device for determining the position of structures on a substrate are known from German published application DE 100 47 211 A1. For details regarding the mentioned position determination, see that document.
Patent document DE 10 2005 052 757 B4 discloses a device for measuring the position of an object, including at least one laser interferometer system for determining a position displacement of the object in at least one spatial direction. The at least one laser interferometer system, together with the object, are accommodated in a climate chamber including an area with air intake apertures and an area with air exhaust apertures. Means are provided to direct at least part of the flow through the climate chamber to the area of the laser axes of the at least one interferometer system during operation.
German published application DE 199 49 005 A1 discloses means and a method for introducing various transparent substrates into a high-precision measuring device. The means is enclosed by a climate-controlled chamber. A magazine having several compartments in which substrate holders for various substrates are deposited is provided, for example, in the climate-controlled chamber. Furthermore, a loading station via which substrates may be introduced into the climate-controlled chamber is provided on at least one outer wall of the climate-controlled chamber. There is also provided an automatic transfer means in the climate-controlled chamber, which removes substrates from the magazine and transports them to the loading station or deposits them on the measurement table of the means.
A coordinate measuring machine is further known from a plurality of patent applications, such as DE 198 58 428 A1, DE 101 06 699 A1 or DE 10 2004 023 739 A1. All mentioned prior art documents disclose a coordinate measuring machine allowing the measurement of structures on a substrate. The substrate is deposited on a measurement table movable in the X-coordinate direction and in the Y-coordinate direction. The coordinate measuring machine is designed such that the positions of the structures and/or the edges of the structures are determined by means of an objective. In order to determine the position of the structures or their edges, the position of the measurement table needs to be determined by means of at least one interferometer. Finally, the position of the edge is determined with respect to a coordinate system of the coordinate measuring machine.
German patent application DE 103 51 848 A1 discloses a system for detecting macrodefects. The system is surrounded by a housing and is subdivided into a first segment, a second segment and a third segment. A stage displaceable in the X-direction and in the Y-direction, on which a wafer is placed, is provided in the second segment. An aspiration means is located in the first segment, which directs the aspirated air via an air guide into the second segment, wherein the air guide includes several air-directing panels so that an air flow is guided in parallel fashion over the wafer.
U.S. patent application no. US 2002/0159207 A1 discloses a ventilation system for lasers in industrial application. Several ventilators are provided in the housing of the laser to provide a corresponding air flow in the housing.